Danger Of Third-Hand Smoke

After finding a link between second-hand smoke and chronic illnesses, the experts now say that there is a possible danger of 'third-hand smoke' as well. According to a new study, nicotine stains on skin, clothing, furniture and wallpaper can react with ambient gases to generate dangerous cancer-causing compounds and chemicals.

"Third-hand smoke" is a name that scientists have given to nicotine residues that cling to surfaces for months. The experts also raise doubts about the safety of "e-cigarettes" - battery-powered devices which are designed to provide a nicotine effect without the risk of developing cancer.

Certain compounds, such as ambient nitrous acid, nitrogen dioxide or ozone,- are present in higher quantities indoors rather than outdoors, said Hugo Destaillats, a principal author of the study that was conducted at Lawrence Berkeley National Laboratory in California, US. This is because these chemicals are generated by combustion from indoor gas supplies, fireplaces or the use of electronic devices.

In their study, the experts tested what actually happens when residual nicotine from tobacco smoke comes into contact with nitrous acid (HONO), a compound typically found in indoor environments. Besides high-tech testing in the laboratory, they also thoroughly analyzed the surface of a stainless-steel glove compartment, as well as its cellulose-based substructure, in a light-duty pickup truck that was regularly used by a heavy smoker. During the three days of an experiment, thirty four cigarettes were smoked inside the truck.

The results revealed that nicotine and HONO did interact, giving rise to the development of chemicals known as tobacco-specific nitrosamines. These compounds, the researchers explained, are designated carcinogens that have been found to cause mutations in animals. It was also revealed that more than 50 per cent of the nitrosamines that had formed during testing environments endured for more than 2 hours after all tobacco smoke had dispersed.

Nicotine, the addictive substance in tobacco smoke, is normally known to be non-toxic in itself. Other chemicals that are released by burning tobacco are generally believed to pose the greatest health hazard from smoking. Unlike second-hand smoke, that can be inhaled unintentionally in public places around smokers, the hazards of third-hand smoke are not so well studied yet. Many factors are involved, starting with the size and ventilation of the indoor environment to the different materials used - microlayers of toxins can accumulate on the skin, upholstery, wallpaper, clothing and hair.

Third-hand smoke is a relatively new concept, but the experts have already established that the most vulnerable population exposed to it is children. "Dermal uptake of the nicotine through a child's skin is likely to occur when the smoker returns, and if nitrous acid is in the air, which it usually is, then TSNAs (tobacco-specific nitrosamines) will be formed," said Thomas J. Glynn, director of cancer science and trends for the American Cancer Society. Mr. Glynn described inquiry into the potential hazards of third-hand smoke as the "next logical step in the exploration of what cigarette smoke does to you."

The findings are published online February 8 in the Proceedings of the National Academy of Sciences journal.